MEF and AssemblyCatalog / AggregateCatalog - visual-studio-2010

Question

I have a simple console app as below (un-relevant code removed for simplicity)
[ImportMany(typeof(ILogger))]
public IEnumerable<ILogger> _loggers {get;set;}
public interface ILogger
{
void Write(string message);
}
[Export(typeof(ILogger))]
public class ConsoleLogger : ILogger
{
public void Write(string message)
{
Console.WriteLine(message);
}
}
[Export(typeof(ILogger))]
public class DebugLogger : ILogger
{
public void Write(string message)
{
Debug.Print(message);
}
}
The code that initialize the catalog is below
(1) var catalog = new AggregateCatalog();
(2) catalog.Catalogs.Add(new DirectoryCatalog(AppDomain.CurrentDomain.BaseDirectory));
(3) //var catalog = new AssemblyCatalog(Assembly.GetExecutingAssembly());
var container = new CompositionContainer(catalog);
var batch = new CompositionBatch();
batch.AddPart(this);
container.Compose(batch);
If the catalog is initialized trough lines 1-2, nothing got loaded into _logger
If the catalog is initialized trough line 3, both logger got loaded into _logger
What's the issue with AggregateCatalog approach?
Thanks

Answer 1

It should work the way you are using it.
However, on line 2 you are creating a DirectoryCatalog, and on line 3 an AssemblyCatalog. Does it work as expected if you change line two into
catalog.Catalogs.Add(new AssemblyCatalog(Assembly.GetExecutingAssembly()));

Answer 2

I found the problem.
It seems DirectoryCatalog(path) search only in DLL by default, and my test program was a console application. And the exports were in EXE (not DLL) so they weren't loaded.
On the other hand, AssemblyCatalog(Assembly.GetExecutingAssembly()), obviously loaded exports from current assembly(which is the EXE).
The solution is to use the other constructor of DirectoryCatalog(path, searchPattern) , and use "*.*" for second param. And it works